1. Field of the Invention
Large Screen Displays (LSD""s) can be defined as any dynamic display which can be viewed by more than one person and is at least two feet wide. The LSD market is diverse, with many differing products and technologies, each having certain strengths and weaknesses, competing to fill the needs of the end user. Applications requiring outdoor use in direct sunlight have traditionally been served best by CRT (Cathode Ray Tube) or LED (Light Emitting Diode) displays, while indoor applications may be served by video walls or front/rear projection systems. The CRT/LED systems, while very bright (typically 4-6 kcd/m2), are very expensive, and offer only marginally acceptable resolution. Moreover, they can only be viewed at a distance because of the need for the RGB (Red-Green-Blue) pixels to optically converge. Thus, they are not cost effective or suitable from resolution or minimum viewing distance criteria for indoor applications. Video walls are adequate for indoor use, but are bulky, not very bright (typically 250 cd/m2), and suffer from the appearance of mullions between each of the displays comprising the wall. Data projectors offer high resolution, yet, because of the constraints of projection systems, are not suitable for many applications. (Typically such a projector must be located several meters or more from the projection surface.)
Fiber optic LSD""s offer substantial improvements over current CRT- and LED-based displays, due to their smaller depth, lighter weight, and elimination of sensitive and expensive electronic components on the surface of the display, while delivering superior resolution and adequate brightness for direct sunlight viewing. Because no RGB convergence is required in fiber optic displays, the minimum viewing distance is considerably less than that of CRT/LED displays.
Fiber optic displays are superior to video walls because they lack mullions, are brighter, more rugged, and are much thinner. Fiber optic displays have an advantage over projection systems in that the display is a xe2x80x9cstand-alonexe2x80x9d unit which can be easily moved and installed at almost any location.
Clearly, fiber optic displays have compelling advantages over competing technologies. Fiber optic displays, however, are not without shortcomings. In fabricating large displays (e.g.,  greater than 100 inches diagonal), the cost of optical fiber becomes considerable. Installing and managing the large amount of optical fiber required for a large display (as many as 120,000 individual fibers for a six by eight foot display) is tedious, time-consuming, and, therefore, costly, inasmuch as each fiber must be cut to length, polished for optimum light transmission, individually inserted into the display and positioned precisely with respect to the display surface, and cemented into place. The opposite ends of the fibers must be arranged in ordered arrays and affixed into position as an input matrix. All of these procedures must be performed without damage to the fiber or its somewhat fragile cladding, in order to assure good light transmission through the fiber. Furthermore, the long, ordered fiber bundles are difficult to manage and susceptible to damage. These problems become particularly severe when designing immersive LSD systems, such as an interactive gaming environment. The purpose of this invention is to address and overcome these and other shortcomings in state-of-the-art manufacturing and assembling of fiber-optic based large screen displays.
This application is a continuation in part of application Ser. No. 09/482,290
2. Description of Related Art
Methods currently used for the manufacture and assembly of large fiber optic display screens are both time-consuming and labor-intensive since each fiber must be installed individually in the display surface and then routed to the input matrix. Furthermore, each fiber must occupy an assigned location in the input matrix, corresponding to an assigned location in the display, in order that an image projected onto the input matrix will be faithfully reproduced on the display. The time and labor required to assemble such displays results in a cost per square foot (of display surface) which is so high as to be essentially non-competitive with other display technologies, thereby effectively eliminating fiber optic displays from this marketplace, even though such displays have many other advantages over competing technologies.
Numerous attempts have been made to develop large screen fiber optic displays which can be manufactured and assembled efficiently and are, therefore, cost-competitive with other display technologies. Although improvements have been made, none of these attempts have been very successful.
U.S. Pat. No. 4,839,635 discloses a fiber optic display system in which optical fibers transfer an image from an input matrix to a display matrix. The display system of this invention is constructed from a large number of small blocks, and purports to be a system which is easily manufactured. However, detailed examination of the patent indicates primarily manual assembly of the many parts. For example, the fibers are handled individually to form groups of eight. A group of eight fibers is manually wrapped with metal foil tape to form a close-packed element of the input matrix while the opposite end of the group is manually disposed into a set of foam blocks which must be cemented together to secure the fibers at the display matrix. It is the purpose of our invention to replace most of these manual operations with machine operations.
U.S. Pat. No. 5,911,024 discloses an apparatus and method of assembly for a fiber optic image enlarger that operates in cooperation with a CRT display. The assembly described involves the formation of individual fibers with male and female ends, making it time consuming, even with automation, to construct a display. The display apparatus described is also costly in terms of the volume of fiber used.
U.S. Pat. No. 5,400,424 discloses a fabrication method for a fiber optic display by joining hexagonal modules with conical projections, each conical projection fixing a discrete optical fiber. The intent of the conical projections is to scatter ambient light in order to enhance the appearance of the display. No mention is made of the problems of fiber management. Moreover, the patent discusses techniques to improve the wide-angle characteristics of the display by making V grooves on each fiber end. Clearly, any manufacturing process that involves handling individual fibers will not be inexpensive or simple to manufacture.
U.S. Pat. No. 3,853,658 discloses a fiber optic image magnifier panel and method for manufacture. In this patent the fibers are threaded through a metal aperture plate. As with the previous patent, concepts for simple and repetitive fiber management are not discussed.
In U.S. Pat. Nos. 4,773,730 and 4,786,139 Sedlmayr discloses an optical light transfer apparatus and method for manufacture. This method entails piecing together multiple wedge-shaped modular fiber display screen devices with the use of many fastening items to form a large screen display. This method involves a high part count and considerable manual assembly, both of which result in a high-cost product.
In U.S. Pat. No. 5,376,201 Kingston discloses a more elegant manufacturing method: an apparatus for forming fiber optic magnification devices. This method involves the simultaneous fabrication of both an input matrix and a display matrix on a large drum, but using a single spool of fiber, which is very time-consuming. Furthermore, a large display requires a significant separation between the input and display matrices, requiring fiber optic cables of eight to ten feet or more in length. Using Kingston""s method would require a drum of six or more feet in diameter to fabricate such cables. The drum itself would be a very costly tool.
U.S. Pat. No. 5,009,475 discloses a molded component in which are formed a plurality of in situ waveguides, preferably tapered. These components can be designed and assembled to function as an image enlarger. Two methods of light propagation are described. First, the authors propose creating hollow light guides and then xe2x80x9cbackfillingxe2x80x9d the guides with an optical plastic or glass which has a higher index of refraction than the surrounding mold material. In practice this is difficult to do because of the long optical paths. Over the length of these optical paths, it is difficult to prevent the formation of bubbles and inhomogeneities in the light transmitting medium, resulting in significant optical losses. The alternative is to use hollow light guides coated with a reflective material. This method as well is difficult to manufacture, and is characterized by large light transmission losses.
This invention discloses a large screen fiber optic display with high fiber density and novel methods for simplifying and thereby cost-reducing the manufacture and assembly of large screen fiber optic displays containing very large numbers of individual fibers, by installing and managing the fibers in subgroups (of approximately 10-100) and groups (of approximately 100-1000) rather than individually.